Huechulafquen Lake is a lake in Neuquén Province, Patagonian Argentina. This glacial lake is located in the Andean mountains in Lanín National Park some 25 kilometres from Junín de los Andes and 60 kilometres from San Martín de los Andes. It is one of Argentina's most important Andean lakes, and is fed by meltwater streams and Lakes Paimún and Epulafquén.

The lake's name is Mapuche, and means long lake, an apt name for this nearly 30 km long, 5 km wide lake, which has a surface area of 104 km².